The Impact of i-Ready In fall 2018 Curriculum Associates conducted comprehensive research into the impact of i-Ready Instruction on student learning gains as measured by the i-Ready Diagnostic. Using i-Ready Diagnostic data from more than one million students who took the i-Ready Diagnostic in the 2017–2018 academic year, our Research team found that students using i-Ready Instruction experienced greater learning gains than students who did not use the program. Learning gains for those students receiving i-Ready Instruction were substantial. Students receiving i-Ready Instruction experienced overall gains of 46% for ELA and 38% for Mathematics relative to students who did not receive i-Ready Instruction across Grades K–8. Effect sizes were positive and generally strong, with the majority exceeding the standard for large for an educational intervention (Cohen’s d of greater than .25). An additional analysis was performed to control for selection bias for Grades 1–8. Again, the research found that students receiving i-Ready Instruction showed greater learning gains than students who did not receive i-Ready Instruction.